Abstract
Caspases are main effectors of apoptosis in metazoans. Genome analysis indicates that there are seven caspases in Drosophila, six of which have been previously characterized. Here we describe the cloning and characterization of the last Drosophila caspase, DAMM. Similar to mammalian effector caspases, DAMM lacks a long prodomain. We show that the DAMM precursor, along with the caspases DRONC and DECAY, is partially processed in cells undergoing apoptosis. Recombinant DAMM produced in Escherichia coli shows significant catalytic activity on a pentapeptide caspase substrate. Low levels of damm mRNA are ubiquitously expressed in Drosophila embryos during early stages of development. Relatively high levels of damm mRNA are detected in larval salivary glands and midgut, and in adult egg chambers. Ectopic expression of DAMM in cultured cells induces apoptosis, and similarly, transgenic overexpression of DAMM, but not of a catalytically inactive DAMM mutant, in Drosophila results in a rough eye phenotype. We demonstrate that expression of the catalytically inactive DAMM mutant protein significantly suppresses the rough eye phenotype due to the overexpression of HID, suggesting that DAMM may be required in a hid-mediated cell death pathway.
Highlights
Programmed cell death in metazoans is mediated by caspases, a family of cysteine proteases, which cleave their substrates following an Asp residue [1,2,3,4]
We show that the DAMM precursor, along with the caspases DRONC and DECAY, is partially processed in cells undergoing apoptosis
The degree of homology between these two caspases is striking given that DAMM does not possess the long prodomain of STRICA
Summary
Programmed cell death in metazoans is mediated by caspases, a family of cysteine proteases, which cleave their substrates following an Asp residue [1,2,3,4]. We show that the DAMM precursor, along with the caspases DRONC and DECAY, is partially processed in cells undergoing apoptosis. Ectopic expression of DAMM in cultured cells induces apoptosis, and transgenic overexpression of DAMM, but not of a catalytically inactive DAMM mutant, in Drosophila results in a rough eye phenotype.
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